The present invention relates generally to electronic ballasts for powering a gas discharge lamp. More particularly, this invention pertains to methods and circuits for an electronic ballast to provide step dimming of a gas discharge lamp.
Public, commercial, and industrial entities often require the use of multiple lighting fixtures to adequately illuminate a facility or an outdoor space. To reduce the power consumed to light these facilities and outdoor spaces, gas discharge lamps are often utilized because of relatively low power consumption when compared to incandescent lamps. Although energy consumption is reduced by the use of these gas discharge lamps, these entities can further reduce energy consumption through the use of two-level or high-low step dimming interfaces to control the inverters in the ballast systems that power the gas discharge lamps. These systems can be used to switch lighting fixtures from a low-wattage energy saving operation (dimming) to a normal wattage operation thus providing significant cost savings.
Unfortunately, prior art step dimming interfaces often require expensive components such as transformers and transistor switches. The initial cost of purchase of ballasts that use prior art step dimming interfaces has resulted in the under-utilization of this important energy efficient technology.
What is needed, then, is a step dimming interface for an electronic ballast that utilizes less expensive components.